A baseline study on the concentration of trace elements in the surface sediments off Southwest coast of Tamil Nadu, India

Heavy metal contamination along different tidal zones of a tropical Bay of Bengal coastal environment influenced by various anthropogenic activities

The spatiotemporal variations of five heavy metals (Cd, Cu, Cr, Pb, and Zn) in the beach sediments along the Tamil Nadu coast sourced from various anthropogenic activities were assessed using atomic absorption spectrophotometry (AAS). Various pollution monitoring indices were computed to clearly understand the metal pollution status along the Tamil Nadu coastline. The metal concentrations in sediments were typically higher in the summer season than in the monsoon season. In the monsoon season, metal concentration followed a decreasing order of Zn > Cr > Cu > Pb > Cd, and in the summer season, the order was Cr > Zn > Cu > Pb > Cd. During the monsoon season, freshwater runoff from the rainfall dilutes the sediments and their trace element load. However, due to a lack of freshwater influx during the summer season, the heavy metals in the sediments get concentrated and showed elevated levels. Geo-accumulation index, ecological risk index, pollution load index, and contamination degree clearly depict that Cd and Pb have higher accumulation and pose greater hazard when compared with other metals. The rivers flowing in the region also transport the heavy metals from the mainland to the estuaries and coastal environments. Metal levels along the Tamil Nadu coast are influenced by various anthropogenic activities persistent along the coastline. Some of the activities that cause metal contamination are mining, milling, electroplating, furnishing, pharmaceutical industries, fishing, harbor activities, urban runoff, and agricultural runoff, which release a variety of toxic metals into the coastal environment.

Trace element concentration and Al/Fe ratio in sediments of the South East Mediterranean Sea

The heavy metals (HMs) concentration range, the metal/Al and metal/Fe value were determined in the sediment in order to evaluate the correlation coefficient of HMs at the regions of South East Mediterranean Sea, Cyprus. The results showed that the mean concentrations of the HMs in the sediment samples followed the order Al > Fe > Mn > Cr > Ni > Zn > Cu > Pb > As>Hg, respectively. The pollution indices of contamination factor (CF), geoaccumulation index (Igeo), enrichment factor (EF), and soil pollution index (SPI) were calculated. The Igeo, CF and EF values for Cu were obtained moderately to strongly polluted, moderate contamination and moderately severe enrichment, respectively. The remaining elements indicated unpolluted or low contamination results. Also, SPI indicated a low level of contamination for the all of the metals. The cluster analysis of data set indicates that the HMs are separated with 50% similarity in two categories of Al category (As, Pb, Cr, Ni) and Fe category (Mn, Zn, Cu, Hg).

Evaluation of metals and trace elements in sediments of Kanyakumari beach (southernmost India) and their possible impact on coastal aquifers

Beach sediments of Kanyakumari at the southernmost India were evaluated for metals and trace elements and to assess their possible impact on coastal ecosystems. Positive correlations (except for Cd and Sr) between them indicated metamorphic lithologies and heavy mineral deposits as possible sources. Significant-extremely high enrichment and very high contamination of Th, Zr, Mo, Ti and U reflected the presence of different heavy minerals. The geo-accumulation index, however, mirrored their variable abundances at different sites. Association of Cd with P suggested the influence of anthropogenic solid waste from fishing industry. It might have caused >41-fold enrichment of Cd and the Fe- Mn-oxides possibly acted as scavengers for 13-fold enrichment of As compared to UCC. Concentrations of Zn and Cr between ERL and ERM in 13% and 93% of the samples, and Ni > ERM in 87% of sediments suggest their bioavailability to seawater with a potential risk for coastal aquifers.

Spatial distribution, origin and contamination assessment of heavy metals in surface sediments from Jangsong tidal flat, Kangryong river estuary, DPR Korea

This study aims to investigate spatial distribution, contamination and origin of heavy metals (Pb, Zn, Cu, Ni, Co and Cr) in surface sediments of Jangsong tidal flat (JTF), Kangryong river estuary, DPR Korea, where has been affected by various mining activities. The spatial diverse of heavy metals are due to differences in their sources and sediment properties. Enrichment factor, geoaccumulation index and ecological risk indexes indicate that JTF is not polluted and has low ecological risk, although slight enrichments occur for some metals. Multivariate analyses revealed that Mn, Ni and Cr originated from lithogenic source, whereas other metals were of anthropogenic origin, among which Fe and Co originated from the iron mine settling pond near JTF, while Pb, Zn and Cu originated from AMD effluent by sulfide mining activity in catchment of JTF. The different transport mechanisms of heavy metals from AMD result in diverse distribution of the metals in JTF.

Microplastic and heavy metal distributions in an Indian coral reef ecosystem

The current study focuses on the occurrence and characteristics of microplastics (MPs) and spatial distribution and pollution status of heavy metals in the water and sediments of the coral reef ecosystems associated with the Tuticorin and Vembar groups of islands in the Gulf of Mannar, southeast India. Mean abundance of MPs varies from 60 ± 54 to 126.6 ± 97 items/L in water and from 50 ± 29 to 103.8 ± 87 items/kg in sediment. Water and sediment samples from the Tuticorin islands contain higher MP concentrations than the Vembar islands. The highest MP were observed in the mainland samples, while MP distributions in the shoreward direction i.e. towards the islands closely reflect those of the mainland (p < 0.05). Polyethylene is the most common polymer, with fibers (1-3 mm) being the most abundant form in water and fragments (3-5 mm) being the most abundant in sediment. Pollution indices such as enrichment and contamination factors indicate moderate contamination of sediments by Zn, Hg, Cd, Pb and Ni. Heavy metal associated with MPs are greater than those in sediments, and this indicates that MP may be a source of metal pollution or that metals from the sediment preferentially partition to MPs. SEM analysis highlights the presence of cracks, protrusions and depositions on the surface of many MPs, indicating partial degradation. EDAX frequently showed the presence of Zn, Cd, Pb, Ni and Fe associated with MP surfaces. This study offers an insight into the level of MPs and associated elements that filter feeding corals in the region are exposed to current.

A baseline study on elemental concentration and potential ecological risk status of the surface sediments of Ashtamudi Lake, south west coast of India

Element concentration (Fe, Mn, Pb, Zn, Cu, Cr, Ni and Co) in the surface sediments of Ashtamudi estuary, Southwest coast of India, has been analyzed to understand the spatial variation and potential ecological risk status. The sediment pollution index and Potential Ecological Risk index suggest that the northeastern part of the estuary exhibits low to moderate polluted sediments with moderate ecological risk. The results of correlation analysis indicate that the natural weathering process and river input play an important role in the distribution of the elements in the surface sediments of the estuary. The extracted factor results indicate that the fine sediment fractions supporting for accumulation of the trace elements, whereas the enriched level of Fe and Mn is chiefly controlled by the riverine process, and other elements are contributed by anthropogenic influences.

Elemental enrichment of sediments in an unprotected shallow groundwater of Lagos and Ogun States, Nigeria

Sediments quality is a good indicator of pollution in a water body where various elements were concentrated. Limited information is available on sediments from hand-dug wells. The present study evaluates sediment samples collected from groundwater of Lagos and Ogun States, Southwest Nigeria. Twenty sediment samples were collected from shallow groundwater, and ten rock samples were also collected from the vicinity of recently dug wells. Trace elements were determined in both the sediments and the rock samples using inductively coupled plasma-mass spectrometry. The enrichment factor was calculated for different elements using Fe, Ti, Mn and Cu as normalizing elements. The order of sediment contamination with each normalizing elements are Cu > Mn > Ti > Fe. The geo-accumulation (Igeo) indexes for Cr, Pb, Cu and Ni are 1.31, 1.05, 1.94 and 1.85, respectively. The Igeo for Lagos sediments is in the order Cr > Pb > Ni > Cu, while in Ogun sediments the order is Cu > Ni > Cr > Pb. The results were compared with Canadian Council of Ministers of Environment values of threshold effect level and probable effect level, which shows the sediments are not toxic. The pollution load index and ecological risk index values are 2.463 and 0.0014, respectively, which further indicates the sediments are not toxic in nature. The major source of most elements in sediments is the host rocks found in the vicinity of the groundwater while high level of some elements recorded in sediments are from the anthropogenic sources.

The sources and ecological risk assessment of elemental pollution in sediment of Linggi estuary, Malaysia

In this study, concentrations of heavy metals, rare earth elements (REEs), Uranium (U) and Thorium (Th) of the actinide group were determined from Linggi estuary sediment samples by neutron activation analysis (NAA) and inductive coupled plasma - mass spectrometry techniques. The geo-accumulation (I_geo) and ecological risk index (Ri) values were calculated to identify the quality status of Linggi estuary sediments. Results indicated Linggi estuary was polluted by arsenic (As), lead (Pb) and antimony (Sb). REEs, U and Th showed significant increase of concentration in Linggi estuary sediments. Ri of Linggi estuary was categorised as low to considerable ecological risk, which indicates no significant to moderate effect on the majority of the sediment-dwelling organisms. Correlation matrix and principal component analysis assessed pollution sources to be both natural and anthropogenic.

Surface sediment properties and heavy metal contamination assessment in river sediments of the Pearl River Delta, China

Concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn), grain sizes, and concentrations of organic carbon (Corg) were measured in 323 river sediment samples from the Pearl River Delta (PRD). Results showed that the heavy metal concentrations in the sediments ranged from 1.6-93 mg/kg for As, 0.04-9.3 mg/kg for Cd, 2-315 mg/kg for Cr, 1.1-352 mg/kg for Cu, 0.01-0.67 mg/kg for Hg, 11-221 mg/kg for Pb, and 11-1234 mg/kg for Zn. The highest values of As, Cr, Cu, Hg, Pb, and Zn appeared in the Beijiang River, whereas Cd was high in the Xijiang River. The overall sediment quality in the area with respect to metal concentrations generally met the primary standard criteria of China (Marine Sediment Quality), except for Cd and Cu. The spatial distributions of the heavy metals were influenced by both grain sizes and Corg concentrations. The Igeo geo-accumulation index indicated that there was no significant Cr, Cu, Hg, or Zn pollution, slight to moderate pollution by As and Pb, and moderate Cd pollution in the study area. Spatial distributions of an eco-toxicological index based on probable effect levels indicated that there was a 21% probability that the combination of the seven metals was exerting a toxic stress in the PRD river sediments.

Assessment of heavy metals in the surface sediments of the Emerald Lake using of spatial distribution and multivariate techniques

The study aims to assess the heavy metals such as cobalt (Co), nickel (Ni), lead (Pb), chromium (Cr), cupper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) from 25 surface sediment samples at different sites of the Emerald Lake, Tamilnadu, India using spatial distribution and multivariate techniques like Pearson correlation matrix and principal component analysis. From the result, the ranges of Fe, Cu, Cr, Mn, Zn, Ni, Co, and Pb are noticed to be 78,128 to 132,876; 314 to 462; 336 to 523; 520 to 701; 20.1 to 53.21; 128 to 215; 91 to 129.9; and 151 to 158 μg g^-1, respectively. The order of the average heavy metals concentration is Fe > Mn > Cr > Cu > Pb > Zn > Co > Ni. From the result, Ni, Cu, Cr, Pb, and Cd are found to be considerably correlated as they are usually related to anthropogenic activities, wastewater, and sewage. From the principal corresponding analysis (PCA) results retrieved from PC3 suggest that Fe, Mn, Cr, Cu, Pb, and Ni have common origin and are mainly due to anthropogenic input, inorganic fertilizers in agriculture, human activities, sewage effluents, traffic, and boat activities. The study relatively provides a significant approach for heavy metal pollution origin in the surface sediment in the Emerald Lake.

Heavy metal assessment in surface sediments off Coromandel Coast of India: Implication on marine pollution

The present study investigates the distribution of heavy metals (Fe, Cd, Co, Cr, Cu, Ni, Zn and Pb) in the surface sediments along the Coromandel Coast of Bay of Bengal as an indicator of marine pollution. Pollution indices such as Contamination factor (CF), Enrichment factor (EF) and Geo-accumulation index (I) were performed to assess the spatial distribution and pollution status of the study area. The heavy metal concentration in the study area is closely associated with grain size and organic matter. Both geoaccumulation index and metal contamination factor indicate that the sediments are free from contamination with regards to the metals Cr and Ni, followed by uncontamination to moderate contamination of Co, Cu and Zn. However, sediments are found to be extremely polluted with respect to Cd and Pb. Factor analysis reveals that the accumulation of these heavy metals in the shelf sediments are due to anthropogenic inputs from the adjacent land area.